The article argues that the U.S. system of educational, scientific& technological, economic and military development, or a tetrad interaction of the above four factors, is a key to understand the U.S. national comprehensive power. Since the end of the Cold War, the U.S. has strategically restructured the policy towards, and budget for, education, science and technology, economy and military development. The report argues that the U.S. has basically maintained its national comprehensive power, retaining its world hegemony. If any of the four factors was seriously hurt, or the tetrad combination could not be achieved, the U.S. national comprehensive power and its world hegemony would be endangered in coming years. <<